Analysis of Classical and Alternate Hexacopter Configurations with Single Rotor Failure

This study examines hexacopter performance in hover and forward flight with single rotor failure. A classical configuration (adjacent rotors spinning in opposite directions) and an alternate configuration are considered. The simulation model uses calculates rotor forces and moments by using blade element theory coupled with a finite-state dynamic inflow model. For the alternate hexacopter, if one of four rotors (out of six) fails, trim is possible in hover and forward flight, and the aircraft remains fully controllable. Recovery from the failure of one of the other two rotors is impossible. For the classical hexacopter, if any of the forward-facing rotors fail, the aircraft can be trimmed in forward flight and is fully controllable. If an aft rotor fails, trim is not possible but the aircraft could be turned around to orient the failed rotor forward. Although the classical hexacopter can be trimmed in hover by turning off the rotor diametrically opposite to the failed rotor, the aircraft is not independently controllable about all axes. In the event of a rotor failure, the classical hexacopter could cruise and land, but it cannot maintain a sustained hover. Power penalties of up to 23% are observed in the event of failure due to increased drag on the operational rotors.